Milk and Dairy FoodsANS 232

August 29 and September 5, 2001

John A. Partridge2100B South Anthony Hall

partridg@msu.edu

Definition of milk.

• "The lacteal secretion, practically free from colostrum, obtained by the complete milking of one or more healthy cows, which contains not less then 3.25% of milkfat and not less then 8.25% milk‑solids‑not‑fat.”

• PMO - Pasteurized Milk Ordinance

• (Food secreted for newborns)

Table 1. Per Capita Consumption of Milk and Milk Products in Various Countries.

Country Beverage Flavored Fermented Cheeses Cream Butter

Finland 186.3 37.1 11.8 1.9 16.0Norway 164.7 14.7 13.5 2.4 8.6Sweden 145.1 27.2 15.4 2.9 8.7Netherlands 91.2 21.0 19.1 14.9 1.0 7.2France 78.1 6.0 13.6 21.8 0.9 14.1Germany 70.1 8.6 10.5 16.8 1.7 14.9Austria 134.1 2.5 9.5 9.6 1.2 8.8Italy 79.5 3.3 17.5 0.8 2.3Greece 54.2 1.7 6.0 22.2 0.3 2.7UK 123.4 0.7 3.6 7.5 0.8 8.4Ireland 182.7 3.2 4.9 0.7 11.8USA 96.9 4.4 2.1 10.9 0.6 3.8Canada 102.6 4.2 3.2 11.7 1.0 7.8India 48.3 4.2 0.2 0.0 21.1Australia 96.0 9.7 3.0 8.5 1.2 6.4Japan 38.0 6.2 7.2 1.0 0.1 1.1

Source: International Dairy Federation

Gross Chemical Composition.

• Average composition.

87.3% Water 3.7% Fat 3.4% Protein 4.9% Lactose 0.7% Ash

SpeciesTable 3. Composition of Milk from Different Mammalian Species

(per 100 g fresh milk).

Protein (g) Fat (g) Carbohydrate (g) Energy (kcal)Cow 3.2 3.7 4.6 66Human 1.1 4.2 7.0 72Water Buffalo 4.1 9.0 4.8 118Goat 2.9 3.8 4.7 67Donkey 1.9 0.6 6.1 38Elephant 4.0 5.0 5.3 85Monkey, rhesus 1.6 4.0 7.0 73Mouse 9.0 13.1 3.0 171Whale 10.9 42.3 1.3 443Seal 10.2 49.4 0.1 502

Cow's MilkBreed

Table 4. Gross composition of milk of various breeds, g/100g.

Body Wt. Milk Yield Fat Protein Lactose Ash Total Solids (kg) (kg) (%) (%) (%) (%) (%)Holstein 640 7360 3.54 3.29 4.68 0.72 12.16Brown Swiss 640 6100 3.99 3.64 4.94 0.74 13.08Ayrshire 520 5760 3.95 3.48 4.60 0.72 12.77Guernsey 500 5270 4.72 3.75 4.71 0.76 14.04Jersey 430 5060 5.13 3.98 4.83 0.77 14.42Shorthorn 530 5370 4.0 3.32 4.89 0.73 12.9

Holstein: 12.16% T.S. x 7360 kg/lactation = 895 kg of total solids produced/lactation (140% of her body wt.!)

Jersey: 14.42% T.S. x 5060 kg/lactation = 730 kg of total solids produced/lactation (170% of her body wt.!)

Grades of Milk

• Grade A– Temperature<45 F(7C) in 2 h– Bacteria 100,000/ml (300,000/ml commingled)– Antibiotics.005 IU detection limit (16mm zone)– Somatic cells 1,000,000/ml

• Grade B or Manufacturing Milk

Facilities and Equipment• Types of milking systems

– Parlors– Around the barn– Bucket

Precautions at the producer level.

• Herd Health – Disease affects milk composition (economic (Ec)

issue)– Antibiotics (public health (PH) issue)

• Added Water (Ec)• Pesticides and other chemicals (PH) • Aflatoxin and other toxins from natural sources (PH)• Sanitation program (PH and Ec)

IV. Milk Processing

• Filtering• Storage (always below 4 C to prevent outgrowth of

Staph. aureus)• Centrifugal Processes• Pasteurization• Homogenization• Cooling• Packaging• Storage and Distribution

Phase I - Preparations

• Sampling– Manhole with dipper

» Odor and appearance» Lab sample for acceptance

– In-line sampler » Inventory & quality control

Co-mingled sample at the plant

Individual farm samples for antibiotics, composition, somatic

cell and bacteria counts

Phase II - Unloading

• Vents open before pumping commences $$$$

• High capacity centrifugal pumps– Up to 600 gallons per minute

• Filtration and/or clarification - optional

Typical Receiving Operations

Phase III - Cleaning the Tanker

• CIP (Clean-in-Place)– safe– effective

• Tagged before leaving plant.

• Pump and exterior of the truck are cleaned while CIP is running.– NOT while milk is unloading.

Receiving Tests

• Titratable Acidity (TA)

• Direct Microscopic Count (DMC)– Bacteria Screening– Somatic Cell Screening

• Antibiotic Residue Screening– Beta Lactam (Penicillin family) every load– Others on a random basis

Silo Tank Equipment• 1. Agitator

• 2. Manhole

• 3. Temperature indicator

• 4. Low-level electrode

• 5. Pneumatic level indicator

• 6. High-level electrode

• Note: Tank vents to the interior of the building.

Milk Storage -Regulatory Requirements

• Cleaned when emptied.

• Must be emptied at least every 72 hours.

• >24 hours in tank– 7-day temperature recording device

Pasteurization– Purposes

• Destroy pathogens --PRIMARY • Destroy spoilage Organisms -- Secondary but very

important – Time-temperature relationships

• Equivalent heat treatments – 145F for 30 m – 161F for 15 s – 191F for 1 s – 212F for .01s

– Cooked flavor and creamline – Overprocessing to obtain shelflife improvements may be

more detrimental to product than helpful.

Plate Heat Exchanger

High-Temperature, Short-Time Pasteurizer

Centrifugal processes.

Separation

Homogenization

– Reduction of fat globules from 3-20µm to <2µm – Same factors that effect the rate of separation in

centrifugal processes• differences in densities • diameter of particles to be separated • residence time• viscosity • drag forces on particle

Raw Milk ( 3-20m globules)

Homogenized milk ( <2m globules)

Fluid Milk Products• Whole Milk

– >3.25% Milkfat; >8.25% Milk-solids-not-fat (MSNF)

– Optional except for school milk: Vitamin D (400 IU/Quart)

• Reduced Fat Milk

– 25% reduction in Fat

• Lowfat Milk

– > 3 grams fat per serving, 1 cup

– Vitamin A (2000 IU/Quart)

– Optional except for school milk: Vitamin D (400 IU/Quart)

• Non-Fat Milk

– > 0.5 grams fat per serving, 1 cup

– Vitamin A (2000 IU/Quart)

– Optional except for school milk: Vitamin D (400 IU/Quart)

Fluid Milk Products• Heavy Cream

– >36% milkfat

• Light Whipping Cream

– >30% but <36% milkfat

• Light Cream

– >18% but <30% milkfat

• Half-and-Half

– >10.5% but <18% milkfat

Butter and Powder

• Butter

• Whole milk Powder

• Non Fat Dry Milk (NFDM) Powder

• Specialty Powders

• Evaporated milk

Cheese

Color is added to the milk and allowedto mix thoroughly.

Rennet is used to coagulate the curd and to separate the whey, or watery portion of milk, from the solids.

After addition of the rennet, the milk is allowed to sit undisturbed. The resulting curd is tested with a knife.

The curds are stirred as they are heatedin a cooking step.

The cut curds are allowed to rest so the culture can grow. The pieces are turned every 15 minutes.

The cheese molds are filled in preparation for pressing.

Pressed, unripened cheese.

Dairy Processing Handbook

Automated Cheddar Cheese Manufacture

Cheese Classification• Fresh Cheeses

– Cottage, Cream

– Acid coagulation

• Bacterial w/o Eyes

– Rennet Coagulation

– Cheddar, Colby, Jack

• Bacterial w/ Eyes

– Carbon Dioxide, Propionic Acid

– Swiss, Dagano

• Mold Ripened

– Blue, Camembert

• Bacteria Smear

– Limburger, Muenster

• Pasta Filata (Pulled Curd)

– Mozzarella, Provalone

Cheese and Related Products cont’d

• Pasteurized Processed

– American Slices

– Velvetta

• Cold Pack

– Chocolate Cheese

– Wispread

• Whey

– Whey powder

– Whey protein concentrate

Fermented Dairy Foods

• Yogurt

– fob vs prestirred

– Spoonable vs drinkable

– Probiotic Cultures

• Buttermilk

• Sour Cream

– Non-fat?

Ice Cream and Frozen Desserts• Compositional Requirements

– Ice Cream

• >10% milkfat; >20% total milk solids

• Must weigh >4.5 lb/gallon

• Must contain >1.6 lb Total Solids/gallon

– Reduced Fat Ice Cream

• 25% reduction in fat content ( <7.5% and >3% milkfat)

– Lowfat Ice Cream

• 3 g fat per serving (½ cup) (<3% milkfat)

– Nonfat Ice Cream

• ½ g milkfat per serving (½ cup)

– NLEA vs. Old Standards of Identity

Ice Cream Ingredients

• Water• Milk-Solids-Not-Fat• Butterfat• Sweetener• Emulsifier• Stabilizer• Flavorings• Colors

The Freezing Process

• Scraped Surface Heat Exchange– Batch– Continuous

• Quality Attributes– Ice crystal size– Overrun– Heat shock